🦠Microbiology
DNA, the blueprint of life, is a complex molecule with a specific structure and function. Its components, including deoxyribose sugar, phosphate groups, and nitrogenous bases, work together to store genetic information. Understanding DNA's structure is key to grasping how it replicates and transmits hereditary traits.
Base pairing rules and the antiparallel structure of DNA are crucial for its function. These features ensure accurate replication and transcription of genetic material. The complementary nature of base pairs and the opposite orientation of DNA strands play vital roles in maintaining genetic integrity across generations.
Chemical Structure and Function of DNA
Components of DNA nucleotides
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- DNA (deoxyribonucleic acid) composed of repeating units called nucleotides
- Each nucleotide consists of three components:
- Pentose sugar called deoxyribose contains 5 carbon atoms in a ring structure
- Phosphate group negatively charged, contributes to the acidic nature of DNA
- Nitrogenous base attached to the 1' carbon of the deoxyribose sugar
- Each nucleotide consists of three components:
- Nitrogenous bases in DNA are:
- Nucleotides linked together by phosphodiester bonds
- Phosphate group of one nucleotide bonds to the 3' carbon of the deoxyribose sugar of the adjacent nucleotide
- Forms the sugar-phosphate backbone of the DNA molecule provides structural support and stability
- Nitrogenous bases face inward, forming the rungs of the DNA ladder (double helix)
- DNA is a type of nucleic acid, a macromolecule that stores and transmits genetic information
Base pairing rules in DNA
- In double-stranded DNA, nitrogenous bases pair with each other according to specific rules
- Base pairing stabilized by hydrogen bonds between complementary bases
- A-T base pairs form two hydrogen bonds weaker bond
- G-C base pairs form three hydrogen bonds stronger bond
- Specificity of base pairing ensures accurate transmission of genetic information during DNA replication
- Each strand of the double helix serves as a template for the synthesis of a new complementary strand ensures faithful copying of genetic material
- Base pairing plays a crucial role in the transcription of DNA into RNA
- During transcription, DNA template strand is used to synthesize a complementary RNA strand (messenger RNA or mRNA)
- Complementary base pairing allows for the storage and transmission of genetic information (genes)
- This principle of complementary base pairing is fundamental to the Watson-Crick model of DNA structure
Antiparallel structure of DNA
- Two strands of the DNA double helix run in opposite directions
- One strand runs in the 5' to 3' direction, while the other runs in the 3' to 5' direction
- Arrangement is referred to as antiparallel opposite orientation of the two strands
- Antiparallel nature of DNA is a result of the way nucleotides are linked together
- Phosphodiester bonds connect the 5' phosphate of one nucleotide to the 3' hydroxyl group of the adjacent nucleotide creates directionality in the DNA strands
- Antiparallel arrangement of DNA strands is essential for the proper functioning of DNA replication enzymes
- DNA polymerases can only synthesize new DNA strands in the 5' to 3' direction adds nucleotides to the growing strand
- Antiparallel nature allows for the simultaneous synthesis of both the leading and lagging strands during DNA replication ensures efficient and accurate replication
- Antiparallel orientation contributes to the structural stability of the DNA double helix
- Hydrogen bonds between complementary base pairs are optimally aligned when the strands are antiparallel maximizes the strength of the base pairing interactions
- Antiparallel arrangement facilitates the separation of DNA strands during replication and transcription
- Enzymes (helicases) can easily unwind and separate the two strands for access to the genetic information
DNA Replication and Genetic Information
- DNA replication follows the semiconservative replication model, where each new double helix contains one original strand and one newly synthesized strand
- The genetic code, stored in DNA, is a set of rules that determines how the sequence of nucleotides is translated into amino acid sequences in proteins
Key Terms to Review (78)
3' to 5' Direction: The 3' to 5' direction refers to the orientation of a DNA molecule, where the 3' carbon atom of one nucleotide is connected to the 5' carbon atom of the next nucleotide. This directionality is essential for the proper replication and transcription of genetic information within the context of DNA structure and function.
5' to 3' Direction: The 5' to 3' direction refers to the orientation of a DNA or RNA molecule, where the 5' (five prime) end is the end with a phosphate group, and the 3' (three prime) end is the end with a hydroxyl group. This directionality is crucial for the proper synthesis, structure, and function of nucleic acids.
Adenine: Adenine is one of the four nitrogenous bases in DNA and RNA, pairing with thymine in DNA and uracil in RNA. It plays a crucial role in encoding genetic information.
Adenine: Adenine is a nitrogenous base that is one of the five main nucleobases found in the nucleic acids DNA and RNA. It is a crucial component of these biomolecules, playing a vital role in their structure and function.
Antiparallel: Antiparallel describes the orientation of the two strands of DNA in which they run in opposite directions. One strand runs 5' to 3', and the other runs 3' to 5'.
Antiparallel: Antiparallel refers to the orientation of the two strands of a DNA molecule, where the sugar-phosphate backbones run in opposite directions. This arrangement is crucial for the structure and function of DNA, as well as the process of DNA replication.
Base Pairing: Base pairing is the fundamental process that allows the double-helix structure of DNA and the secondary structure of RNA to form. It refers to the specific interactions between the nitrogenous bases on complementary strands of nucleic acids, which are essential for the storage and transmission of genetic information.
Base sequence: A base sequence is the order of nucleotide bases in a DNA or RNA molecule. It determines the genetic information carried by that molecule.
Campylobacter jejuni: Campylobacter jejuni is a Gram-negative, spiral-shaped bacterium that is one of the most common causes of bacterial gastroenteritis worldwide. It typically infects the gastrointestinal tract but can sometimes cause more severe systemic infections.
Chargaff: Chargaff was a biochemist who discovered that DNA from any cell of any organism has a 1:1 ratio of pyrimidine and purine bases. This finding, known as Chargaff's Rules, was crucial for the discovery of the double helix structure of DNA.
Chargaff’s rules: Chargaff's rules state that DNA from any species of any organism should have a 1:1 ratio of pyrimidine and purine bases, specifically, the amount of guanine is equal to cytosine and the amount of adenine is equal to thymine. This finding was crucial for understanding the double helix structure of DNA.
Colonization factor (CF): A colonization factor (CF) is a protein or molecule that enables bacteria to adhere to host cells, facilitating infection and colonization. These factors are critical for the establishment of bacterial infections and their persistence within the host.
Complementary base pairing: Complementary base pairing is the specific hydrogen bonding between purines and pyrimidines in DNA. Adenine pairs with thymine, and guanine pairs with cytosine.
Complementary Base Pairing: Complementary base pairing is a fundamental principle of DNA structure and replication, where the four DNA bases (adenine, thymine, guanine, and cytosine) form specific pairs that hold the two strands of the DNA double helix together. This pairing pattern is essential for the accurate storage and transmission of genetic information.
Complementary base pairs: Complementary base pairs are specific nitrogenous bases in DNA that form hydrogen bonds with each other; adenine pairs with thymine, and cytosine pairs with guanine. This pairing is essential for the double-helix structure of DNA and accurate replication.
Cryptosporidium parvum: Cryptosporidium parvum is a unicellular eukaryotic parasite that causes cryptosporidiosis, primarily affecting the intestines. It is known for its resilience in water and resistance to many conventional disinfection methods.
Cytosine: Cytosine is one of the four main nitrogenous bases found in DNA and RNA. It pairs with guanine through three hydrogen bonds.
Cytosine: Cytosine is one of the four primary nitrogenous bases found in nucleic acids, specifically DNA and RNA. It is a pyrimidine derivative that plays a crucial role in the structure and function of these genetic materials.
Denaturation: Denaturation is the process where proteins or nucleic acids lose their structure due to external stress, such as heat or chemicals. This loss of structure results in a loss of function.
Deoxyribonucleic acid (DNA): Deoxyribonucleic acid (DNA) is a molecule that carries the genetic instructions for life. It is composed of two strands forming a double helix, with each strand made up of nucleotides containing a phosphate group, a sugar molecule, and a nitrogenous base.
Deoxyribonucleotides: Deoxyribonucleotides are the building blocks of DNA, consisting of a deoxyribose sugar, a phosphate group, and a nitrogenous base. They link together to form the DNA polymer through phosphodiester bonds.
Deoxyribose: Deoxyribose is a five-carbon sugar molecule that serves as the backbone of DNA. It is an essential component of nucleotides, which form the structural unit of DNA.
Deoxyribose: Deoxyribose is a five-carbon sugar that serves as the backbone of the DNA molecule. It is a key structural component that distinguishes DNA from its counterpart, RNA, which contains the sugar ribose instead.
DNA: DNA (Deoxyribonucleic Acid) is the hereditary material in almost all living organisms, carrying genetic information essential for growth, development, and reproduction. It consists of two strands forming a double helix structure.
DNA Polymerase: DNA polymerase is a critical enzyme responsible for the replication and repair of DNA, ensuring the accurate transmission of genetic information during cell division. It plays a central role in the structure and function of DNA, as well as the overall function of genetic material within cellular genomes.
DNA Replication: DNA replication is the fundamental process of creating two identical copies of a DNA molecule from a single parent molecule. This process is essential for cell division, growth, and the maintenance of genetic information in all living organisms.
Double helix: The double helix is the structure formed by double-stranded molecules of nucleic acids such as DNA. It consists of two complementary strands that coil around each other to form a helical shape.
Double Helix: The double helix is the unique three-dimensional structure of DNA, the genetic material found in all living organisms. It consists of two complementary strands of nucleic acids that wind around each other, forming a spiral staircase-like shape.
DsDNA: Double-stranded DNA (dsDNA) consists of two complementary strands that form the double helix structure of DNA. It is the genetic material for many organisms, including some viruses.
Entamoeba histolytica: Entamoeba histolytica is a protozoan parasite that causes amoebic dysentery in humans. It primarily infects the intestines, leading to severe gastrointestinal symptoms.
Enterotoxigenic E. coli: Enterotoxigenic E. coli (ETEC) is a type of Escherichia coli bacteria known for producing toxins that target the intestines, leading to diarrhea. It is a major cause of traveler's diarrhea and can be life-threatening, especially in children in developing countries.
ETEC: Enterotoxigenic Escherichia coli (ETEC) is a type of E. coli bacteria that produces enterotoxins leading to diarrheal illness. It is commonly associated with traveler's diarrhea and affects the small intestine.
Franklin: Rosalind Franklin was a British scientist whose X-ray diffraction images of DNA were critical in the discovery of its double helix structure. Her work provided key insights into the molecular structure of DNA.
Genetic Code: The genetic code is the set of rules by which information encoded in genetic material (DNA or RNA sequences) is translated into proteins. It establishes the correspondence between the sequence of nucleotides in nucleic acids and the sequence of amino acids in proteins, allowing cells to synthesize specific proteins necessary for their structure and function.
Giardia lamblia: Giardia lamblia is a unicellular eukaryotic parasite that causes giardiasis, a common gastrointestinal infection. It primarily inhabits the small intestine of humans and other mammals.
Gosling: Gosling refers to Rosalind Franklin's assistant, Raymond Gosling, who played a significant role in capturing Photo 51. This X-ray diffraction image was critical in elucidating the double-helix structure of DNA.
Guanine: Guanine is one of the four main nucleobases found in DNA and RNA, represented by the letter G. It pairs with cytosine (C) through three hydrogen bonds in the DNA double helix.
Guanine: Guanine is a purine nucleobase that is one of the four main chemical building blocks of DNA and RNA. It is a key component in the genetic code and plays a vital role in the structure and function of nucleic acids.
Heat-labile enterotoxin (LT): Heat-labile enterotoxin (LT) is a toxin produced by certain strains of Escherichia coli. It is sensitive to heat and can cause severe diarrhea by increasing cAMP levels in host cells.
Heat-stabile enterotoxin (ST): Heat-stabile enterotoxin (ST) is a type of exotoxin produced by certain bacteria, such as Escherichia coli. It is resistant to heat and can cause severe gastrointestinal disturbances.
Helicase: Helicase is an enzyme that plays a crucial role in the process of DNA replication by unwinding the double-stranded DNA molecule, allowing the replication machinery to access and copy the genetic information.
Hydrogen Bond: A hydrogen bond is a type of dipole-dipole attraction that occurs when a hydrogen atom covalently bonded to a highly electronegative element, such as oxygen, nitrogen, or fluorine, is attracted to another nearby highly electronegative element. This intermolecular force is crucial in determining the structure and function of biological macromolecules, particularly DNA.
Lagging Strand: The lagging strand is one of the two strands of DNA that is synthesized discontinuously during the DNA replication process. It is the strand that is replicated in the opposite direction to the movement of the replication fork, resulting in the formation of Okazaki fragments that are later joined together.
Leading Strand: The leading strand is the continuously synthesized DNA strand during the process of DNA replication. It is the strand that is replicated in the same direction as the overall replication fork movement.
McClintock: Barbara McClintock was an American scientist who won the Nobel Prize in Physiology or Medicine in 1983 for discovering genetic transposition, or 'jumping genes.' Her work with maize demonstrated that genes could change positions on chromosomes, influencing gene expression and mutation.
Nitrogenous base: Nitrogenous bases are organic molecules that contain nitrogen and act as the building blocks of nucleic acids, such as DNA and RNA. They play a crucial role in encoding genetic information.
Nitrogenous Base: A nitrogenous base is a type of organic compound that contains at least one nitrogen atom and is a key structural component of nucleic acids, such as DNA and RNA. These bases play a crucial role in the storage and transmission of genetic information within living organisms.
Nitrogenous bases: Nitrogenous bases are organic molecules that contain nitrogen and act as the fundamental building blocks of nucleic acids like DNA and RNA. They pair with each other to form the rungs of the DNA double helix, enabling genetic information storage and transfer.
Nucleic acid: Nucleic acids are biopolymers essential for all known forms of life, composed of monomers called nucleotides. They include DNA and RNA, which store and transmit genetic information.
Nucleic Acid: Nucleic acids are large biomolecules composed of monomeric units called nucleotides, which are essential for the storage and transmission of genetic information in living organisms. They play a crucial role in the structure and function of DNA and RNA, the two main types of nucleic acids.
Nucleoside: A nucleoside is a molecule consisting of a nitrogenous base attached to a five-carbon sugar (ribose or deoxyribose). It lacks the phosphate group that distinguishes it from a nucleotide.
Nucleotide: A nucleotide is the basic building block of nucleic acids, such as DNA and RNA. It consists of a nitrogenous base, a five-carbon sugar, and one or more phosphate groups.
Nucleotide: A nucleotide is the fundamental building block of nucleic acids, such as DNA and RNA. It consists of a nitrogenous base, a pentose sugar, and a phosphate group. Nucleotides play a crucial role in various biological processes, including energy production, cellular signaling, and the storage and transmission of genetic information.
Pauling: Linus Pauling was a renowned chemist and biochemist who made significant contributions to the understanding of chemical bonds and molecular structures, including those in DNA. His work laid the groundwork for future discoveries in DNA structure and function.
Phosphate Group: A phosphate group is a molecular structure consisting of a central phosphorus atom covalently bonded to four oxygen atoms. This functional group is ubiquitous in biological systems, playing crucial roles in the structure and function of lipids, DNA, and RNA.
Phosphodiester Bond: A phosphodiester bond is a covalent chemical bond that links the phosphate group of one nucleotide to the sugar (deoxyribose or ribose) of the next nucleotide, forming the backbone of DNA and RNA molecules. This bond is essential for the structural integrity and information storage capabilities of genetic material.
Phosphodiester bonds: Phosphodiester bonds are covalent bonds that connect the 5' carbon of one nucleotide to the 3' carbon of another, forming the sugar-phosphate backbone of DNA and RNA. These bonds are crucial for the stability and integrity of nucleic acid structures.
Purine: Purines are a class of nitrogenous heterocyclic compounds that are essential components of nucleic acids, such as DNA and RNA. They serve as the building blocks for the genetic material that stores and transmits hereditary information within living organisms.
Purines: Purines are a type of nitrogenous base found in nucleotides, which are the building blocks of DNA and RNA. They include adenine (A) and guanine (G).
Pyrimidine: Pyrimidines are a class of organic compounds that contain a six-membered aromatic ring with two nitrogen atoms. They are one of the two families of nitrogenous bases found in nucleic acids, the other being purines. Pyrimidines play a crucial role in the structure and function of DNA and RNA.
Pyrimidines: Pyrimidines are one of the two types of nitrogenous bases found in nucleic acids, characterized by a single six-membered ring structure. They include cytosine, thymine (in DNA), and uracil (in RNA).
Replication: Replication is the process by which a cell makes an exact copy of its DNA. It is a critical mechanism that ensures genetic information is accurately transmitted to daughter cells during cell division.
Rich: In molecular biology, 'rich' refers to regions of DNA that are abundant in certain types of bases, such as GC-rich or AT-rich sequences. These regions have specific structural and functional implications for the genome.
Salmonella: Salmonella is a genus of rod-shaped, Gram-negative bacteria that cause gastrointestinal infections in humans and animals. These bacteria are known for their ability to cause foodborne illness through the ingestion of contaminated food or water.
Semiconservative Replication: Semiconservative replication is the process by which DNA makes copies of itself during cell division, where the original double-stranded DNA molecule is used as a template to produce two new, identical DNA molecules. This process ensures the accurate transmission of genetic information from one generation of cells to the next.
SsDNA: ssDNA stands for single-stranded DNA, which is a DNA molecule consisting of only one strand as opposed to the normal double-stranded structure. It plays crucial roles in viral replication and various molecular biology techniques.
Sugar-phosphate backbone: The sugar-phosphate backbone is the structural framework of DNA and RNA. It consists of alternating sugar and phosphate groups that provide stability and support to the nucleotide chains.
Sugar-Phosphate Backbone: The sugar-phosphate backbone is the structural framework that forms the backbone of DNA and RNA molecules. It is composed of alternating sugar (deoxyribose or ribose) and phosphate groups, which provide the structural support and directionality for the nucleic acid strands.
Thymine: Thymine is one of the four nucleobases in the DNA molecule, symbolized by 'T'. It pairs with adenine (A) through two hydrogen bonds to help stabilize the nucleic acid structures.
Thymine: Thymine is a pyrimidine nucleobase that is one of the four primary nucleic acid bases found in DNA. It forms base pairs with the purine nucleobase adenine, and its presence and pairing is essential for the structure and function of DNA molecules.
Transcription: Transcription is the process by which a segment of DNA is copied into RNA by the enzyme RNA polymerase. It is the first step in gene expression, allowing genetic information to be transcribed for protein synthesis.
Transcription: Transcription is the process by which the genetic information encoded in a DNA sequence is copied into a complementary RNA molecule, which then serves as a template for the synthesis of proteins. It is a fundamental step in the central dogma of molecular biology, where DNA is transcribed into RNA, which is then translated into proteins.
Transposons: Transposons, also known as jumping genes, are DNA sequences that can change their position within the genome. They play a significant role in genetic diversity and evolution by causing mutations and altering the cell's genetic identity.
Vertical gene transfer: Vertical gene transfer is the transmission of genetic material from parent to offspring during reproduction. It ensures the continuity of genetic information across generations.
Watson and Crick: Watson and Crick are the scientists who discovered the double helix structure of DNA in 1953. Their model explained how genetic information is stored and replicated.
Watson-Crick Model: The Watson-Crick model is a structural model that describes the double-helix configuration of DNA, the genetic material found in all living organisms. It was proposed by James Watson and Francis Crick in 1953 and has become the fundamental framework for understanding the structure and function of DNA.
Wilkins: Maurice Wilkins was a molecular biologist and biophysicist who contributed significantly to the discovery of the DNA double helix structure. He shared the 1962 Nobel Prize in Physiology or Medicine with Watson and Crick.
X-ray diffraction: X-ray diffraction is a technique used to determine the atomic and molecular structure of a crystal by measuring the angles and intensities of X-rays that are diffracted upon hitting the crystal. This method allows scientists to visualize the 3D structure of molecules such as DNA.
3' to 5' Direction
See definitionThe 3' to 5' direction refers to the orientation of a DNA molecule, where the 3' carbon atom of one nucleotide is connected to the 5' carbon atom of the next nucleotide. This directionality is essential for the proper replication and transcription of genetic information within the context of DNA structure and function.
Term 1 of 78
3' to 5' Direction
See definitionThe 3' to 5' direction refers to the orientation of a DNA molecule, where the 3' carbon atom of one nucleotide is connected to the 5' carbon atom of the next nucleotide. This directionality is essential for the proper replication and transcription of genetic information within the context of DNA structure and function.
Term 1 of 78
